Might be useful for search. (not necessarily just web search, but ecommerce as well)

For example, instances of "aqua" should probably match the search query "blue". Google seems like it may already be that advanced, but other search engines perhaps not. Large-scale search engines probably would keep this in their own DB, though.

No idea yet. Seems to have gotten a good response from hacker news/product hunt crowd. I mainly built it because I needed it for another project.